1. Technical Field
The present invention relates to treadle drive systems and in particular to a treadle drive system having a positive engagement clutch.
2. Description of the Prior Art
Exercise and ecologically beneficial transportation are two major concerns today. Although it is too early to determine all of the long range effects of various types of exercise, there seems to be a number of injuries associated with Jogging or running and also with many other sports. Bicycling is very popular as a means of exercise and an ecologically sound mode of transportation. Again, there seems to be some evidence of the adverse strain developed in joints and muscles as a result of the joint flexion and muscle strain associated with the rotary motion of pedaling a traditional bicyle. Walking seems to be the primary exercise and mode of transportation agreed upon as healthy and ecologically sound with the least likelihood of joint injury and muscle strain. Not everyone is able to enjoy the health benefit of walking equally well, particularly those with injuries or disabilities.
In many locations away from traditional power sources, and particularly locations remote from electrical power lines, man-made rotary sources of power are indespensable. Producing such power requires an output of energy and when human power is applied the problems described above still apply in terms of a healthy efficient way for people to apply the power.
In traditional pedal drive systems, a rotary motion is imparted to the pedals, wherein power is imparted primarily on the down stroke with a variable lever effect. In a standing position to gain maximum power from the weight of the body, the circular motion is not as easily imparted, because of much flexing action of the foot and knee due to the complete circular travel of the foot.
In prior art U.S. Pat. No. 4,828,284, issued to Sandgren, a treadle drive system used in a standing position with a comfortable up and down movement imparts a maximum force on a downward stroke using the full weight of the body. Extreme flexing is avoided and only a natural minor bending of the knees is required as in walking or stair climbing. Motion and energy are produce by constant length levers or treadles which require an alternating right and left foot downward thrust with one foot in a natural stepping fashion with the opposite foot returning vertically to an elevated position for the next thrust. The drive sprocket of the Sandgren patent uses a non-reversing clutch which allows for forward motion only and not for backing up the vehicle.
In the Sandgren patent, the chain ends are attached to the rear of the treadles which pivot from a hinge positioned back from the forward steering column of the vehicle. Having the chain ends attach at the midpoint in the rear of each treadle creates a separation between the two ends of the chain requiring two crossover sprockets.